Many vehicles currently on the market are equipped with different types of active safety equipment in order to support the driver in certain traffic situations. For this purpose, it is necessary to ascertain the vehicle environment and detect objects and situations. A component of corresponding safety systems, therefore, is a group of sensors for continuously monitoring the vehicle environment.
In scenarios in which a vehicle approaches an object (e.g., a foreign vehicle) located in the corresponding vehicle trajectory or lane, the functionality of automatically (without driver intervention) avoiding a collision with the relevant object can be provided. A corresponding driver assistance system (DAS) is known in the prior art and generally comprises multiple components or sub-functions.
For example, a DAS monitors the vehicle environment using one or more sensors (e.g., radar, camera, lidar), wherein map data or other sources of information such as, e.g., vehicle-to-vehicle communication, can also be used. The sensor information may then combined or fused in order to generate an environmental model, which makes it possible to calculate the path of the vehicle as well as the position of objects in the path of the vehicle. The corresponding objects are then evaluated in terms of their position and velocity relative to the intended path of the vehicle, wherein objects that are located within the intended path of the vehicle or that are approaching the path of the vehicle are classified as possible target objects for further evaluation by the DAS. After that, the relative positions, relative velocities, and sizes of the relevant target objects can be used for calculating a weighting factor (e.g., relating to the collision risk, the possibility of the collision, the time to collision, etc.) in order to provide trigger points for activating actuators in the vehicle (steering system, brakes, vehicle settings, etc.), e.g., for a steering intervention, a braking intervention, or adjusting certain vehicle parameters.
A further sub-function of a DAS is based on the reaction of the driver, wherein the manner in which the driver acts directly upon the vehicle by actuating the steering wheel or pedals (brakes, clutch, and gas pedal) is monitored. If the driver reaction ascertained on the basis of the available driver-monitoring sensors indicates a maneuver for collision avoidance, a trigger signal for activating actuators in the vehicle for collision avoidance can also be generated.
A further sub-function of a DAS is based on the dynamic vehicle state of the particular vehicle equipped with the system according to the invention. Known vehicle sensors, e.g., for measuring the vehicle velocity, the yaw rate, and the lateral acceleration, determine the dynamic state of the vehicle. In this case, the activation for collision avoidance can be limited, in particular, to a certain velocity range.
A further sub-function of a DAS includes the calculation of a suitable collision avoidance path or an alternative route. In this case, the linked environmental and object information is used for calculating a suitable path for collision avoidance or for an evasive maneuver. Such a calculation of one or more alternative routes can be carried out using splines, logic functions, or polynomials, as is well known in the art. The basic conditions that apply in this case include collision avoidance with a target vehicle or foreign vehicle, and physical limits such as, e.g., a maximum lateral acceleration, friction, vehicle parameters, etc. In this case, either a suitable alternative route can be selected from a group of vehicle paths (and with consideration for further optimization criteria) or a single alternative route can be determined from the beginning as the optimal vehicle path based on the basic conditions.
A further sub-function relates to the control of one or more actuators or a combination of actuators. The actuators utilized for collision avoidance are typically steering system components and brakes. However, certain vehicle parameters or settings such as, e.g., the settings of a spring-and-shock absorber system and the setting of a steering ratio for supporting a collision avoidance maneuver may also be adjusted as necessary.
In addition, it is known to provide the driver with the opportunity to maintain complete control over the vehicle by disabling the activated collision avoidance system or DAS.
DE 10 2011 106 520 A1 discloses, inter alia, a method for avoiding a collision of a vehicle and a driver assistance system for a vehicle, wherein the actuation of the brake pedal is continuously detected, wherein a collision risk is deduced when the brake pedal is rapidly actuated. Furthermore, the position and movement of objects in the vehicle environment are detected and evaluated in terms of the collision risk. If a collision risk is identified, an evasive maneuver of the vehicle is automatically carried out when the evaluation of the collision risk reveals that a collision can be avoided by means of an evasive maneuver, but not by means of a braking maneuver.
DE 10 2004 056 027 A1 discloses a method and a vehicle assistance system for avoiding collisions or for reducing the collision severity of a vehicle, wherein the assistance system carries out an automatic steering- and/or braking intervention on the basis of the evaluation of the present and future position of objects relative to the vehicle when, according to the evaluation, a collision with an object is unavoidable without an intervention into the system.
Reference is made to DE 10 2008 040 241 A1, DE 10 2010 006 215 A1, U.S. Pat. No. 8,918,255 B2, U.S. Pat. No. 8,423,277 B2, DE 10 2012 017 628 A1 and DE 10 2004 056 027 A1 as the further prior art.